Question for you fellow v-10ers. It was about 38 degrees and foggy and very damp this morning here in WI. My pickup sat since last sunday outside and when i started this morning it had a misfire. It has done this probably about 4 times since I've had it but only when the humidity is very very high. I just ended up taking my car to work anyway not a big deal because I'd put money on it that when I start it after work when it's less humid that it will run like a champ(like every time before) and it won't happen again for who know's how long. It has about 107K on it and it's never been touched exept for the normal IAC, DPFE sensor. (great motor) I put plug's in it around 60K, and I put new boot's on the coils right away with di-electric grease(coils are all origional). I was thinking of just buying one coil and doing the old swaparoo to find out witch coil it was but then it so intermittent I haven't had a chance. This is the weird part, it misfires at an idle and if i give it light throtle it will run smooth(this is in park). While driving it will run fine at steady light throtle but once you try gassing it a little harder it start's missfiring(especially in OD). My question is do you guy's think that the MAF could cause a problem like this or is it just a touchy coil? I spray my MAF off every few months to keep it clean and I run a OEM paper filter.

Sorry for the long post, just looking for some ideas.

 

I have had this problem intermittantly but it always goes away almost immediately. It sort of chugs a bit until it feels like it cleans itself out and then it's fine. And never while driving had I had this happen. Your problem is fairly common with the exception of it lasting while driving. Ken

 

Now it's time to spray your coils.

All of your symptoms are consistent with a weak coil; and if the defect is most evident when it is wet, then duplicate the conditions that are causing the failure to show up.

Put some water in a spray bottle, and spray a fine mist on the coils one at a time until one of them starts to misfire.

 

Thanks for the reply's.

I have done that before with regular spark plug wires at night but not the COP's. I havent been home from work yet so not sure what will happen but in a way I'm kind of hoping that it's still missfiring so I can troubleshoot it. Most likely it will not be(usually is fine next time I start it) so I might have to try Stan's advise with the spray bottle. Ken I have also once or twice had mine run rough for about 20-30 seconds and then clear up too. I seemed that it did that after sitting for a couple of weeks something. I figured it had something to do with the computer adjusting the timing after startup or something. We'll I will let you guy's know what happens and thanks for the advise. I'm open for some more Idea's from everybody too.

Later

Brad

 

Great question. I have this issue intermittently when I fire my truck up in the morning when it's cold, (mind you az cold is like 40, have ~65k miles on it). It's even died a couple of times. I'm pretty sure it's not the MAF cuz I just put a new in like 4 months ago (busted the old one trying to clean it, ugg). Maybe it's time I put some new plugs, wires, coils in it...

 

Silverbullet,

I'm sure you have heard of the good ol' Idle Air Controler selonoids(IAC) that are known to get carboned up. If your's dies ocationally it might be something to think about. They won't idle if the IAC is bad, mine went at about 50K. They arent too horrible to change for around $50. good luck

 

It's only happened twice where it died, but the mornings seem to be rough on it. It starts up and then coughs a bit. I haven't heard of IAC before, so thanks for the heads up, I'm gonna look into that.

 

Sound's like that could be your issue as mine only died or coughed every so often too(more in colder weather). It is right on the back of the intake, it's not too hard to change just try not to drop the little bolts that hold it on when you remove them. If I were you I would do a search in this forum for IAC and see what you come up with(there is some detailed instructions with pictures from some fellow FTE'ers). It is a regular issue that people have with both v-8's and v-10's. I would bet that is it.

 

Oh yah,

I almost forgot. I FINALLY FIXED MY MISSFIRE ON FRIDAY NIGHT!!!!!!! Well I got home from work and needed to run to town and it was still crappy out side with rain and damp. I started the truck and well, it ran fine. DARNIT!!! On the way to town though my missfire reappeard. I went to autozone and there were no codes so I just bought a coil anyway $45 wasn't too bad I didn't think. Got home and begun swapping and sure enough it was the 3rd one back on the drivers side. Only took 25 min to figure out(glad I started on the drivers side) Put the new one in and no missfire, just too be sure I put the old one back in and well I had a missfire. SWEET!! All these years that stupis coil has acted up like that in damp weather. Anyway thanks for all the help guy's. I guess I can't complain too much with 107k on all origional coils can I. Thanks

Brad

 

That's great glad to hear it worked for ya. I'm definitely going to have to look into mine soon. My gas mileage has gone down the crapper. I went from getting about 300 miles out of a tank (38gal) to about 250 or so. Not sure what's goin' on but somethin' isn't right. It feels like it's running good still (I could be used to the way it runs though) but I think it's just time for a tune up.

 

I guess I would check your air filter and take some non-residue electronics cleaner and spray your Mass Airflow Sensor good and let it dry for a couple of minutes. I do mine every few months just to keep the grime off of it. I had an K&N but I took it out after one long trip up north quad running, on the way back I kind of had poor performance(and bad milage). Turned out spraying my MAF fixed my issues, must have been some of the K&N oil on the MAF. I went back to a paper filter now. That might cause your milage to suck, I usually can get 270-300 mi per tank(29 gallon, short box). That's mixed city and highway and average pedal. I think it's between 12-13mpg usually.

 

I have a K&N fipk on it now (have had it 4 years). What did you spray the MAF with? I just replaced the MAF about 6 months ago if that makes any difference.

Most of my bad mileage is due to my heavy foot (not to mention running 37's with 3.73 gears) but the needle is moving to E faster than ever.

 

Well I think you could probably use anything that doesn't leave a residue(small film) that can cause you the same or more problems. I can get you the name if you want but it is just Non-residue Electronics contact cleaner. I got it a Farm&Fleet but you should be able to get it at Radio shack and maybe even Walmart. I have also used non-residue flux remover from work once without problems. I work with circut boards and use it frequently. That may not be your problem since you have just replaced it but it's worth a shot I guess. Did you replace the MAF with the same size(OEM)? I've heard if you get a bigger one that you need a chip or a computer reflash to adjust the mixture.

 

Replaced it with the same size (OEM). Thanks for the info, I'll try it and see if it helps.